P0303

DTC P0303: Cylinder 3 misfire detected

NOTE: If some of the DTCs listed below are stored at the same time as a misfire DTC, troubleshoot those DTCs first, then recheck for the misfire DTC.

P0131, P0132: Primary HO2S
P0171, P0172: Fuel supply system
P0401: EGR system
P1361, P1362, P1366, P1367: TDC1/TDC 2 Sensor

1. Start the engine, listen for a clicking sound at the fuel injector in the problem cylinder.
Does it click?
YES-Go to step 2.
NO-Go to step 11.
2. After checking and recording the freeze data, do the PCM Reset Procedure. If there is no freeze data of misfiring, just clear the DTC.
3. Exchange the spark plug from the problem cylinder with one from another cylinder.
4. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
5. Check the DTC and the Temporary DTC with the scan tool.
Is DTC P0301, P0302, P0303 or P0304, P0305 or P0306 or Temporary DTC P1399 indicated?
YES-Go to step 6.
NO-Intermittent misfire due to spark plug fouling, etc. (no misfire at this time).
6. Determine which cylinder(s) had the misfire.
Does the misfire occur in the other cylinder whose spark plug was exchanged?
YES-Replace the faulty spark plug.
NO-Go to step 7.
7. Exchange the fuel injector from the problem cylinder with one from another cylinder.
8. Let the engine idle for two minutes.
9. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze date.
Is DTC P0301, P0302, P0303, P0304, P0305 or P0306 or Temporary DTC P1399 indicated?
YES-Go to step 10.
NO-Intermittent misfire due to bad contact in the fuel injector connector (no misfire at this time).
10. Determine which cylinder(s) had the misfire.
Does the misfire occur in the other cylinder whose fuel injector was exchanged?
YES-Replace the faulty fuel injector.
NO-Check the engine compression and cylinder leak down.
11. Check for an open or short in the harness between PCM and the fuel injector.
Are the wires OK?
YES-Replace the fuel injector. If the symptom still exists, substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.
NO-Repair open or short in the wire.